Field of the Disclosure
The present disclosure relates to a setting method and a setting apparatus for setting a frequency band to be removed for a damping filter provided in a positioning apparatus that controls a drive motor of a rotary table device including a base, a table which is rotatably held by the base and on which an object is to be placed, and the drive motor which rotates the table with respect to the base, as well as a positioning apparatus provided with the setting apparatus.
Background of the Disclosure
For example, in the field of machine tool, the above-described positioning apparatus has been generally used for positioning control of a feed device or a rotary table. A known example of such a positioning apparatus is the one disclosed in Japanese Unexamined Patent Application Publication No. 2009-101444, which controls a biaxial unit having a trunnion structure, which is provided on a machine tool such as a 5-axis control vertical machining center. The positioning apparatus includes a function generator, a position controller, a speed controller, and a torque/current controller, and controls a motor rotating the trunnion in accordance with a signal output from the torque/current controller.
Specifically, in this positioning apparatus, a position command is generated based on an NC command output from an NC device by the function generator, a speed command is generated based on the generated position command and a position gain by the position controller, a torque command is generated based on the generated speed command and a speed gain by the speed controller, a drive torque signal is generated based on the generated torque command and a torque gain by the torque/current controller, and a current corresponding to the signal is supplied to the motor, whereby the motor is driven.
Further, the positioning apparatus has an angle error estimator provided therein which calculates an angle error caused by elastic deformation of the trunnion and compensates for the angle error; the angle error estimator calculates the angle error Δθ by the following equation:Δθ=(Tm−Jm·α)/KθR, where Jm is an inertia of the turning shaft portion or the bearing, Tm is a torque command output from the speed controller, α is a rotational angular acceleration, and KθR is a torsional rigidity coefficient.